1. Field of the Invention
The present invention relates to a heat treatment method which irradiates a silicon substrate such as a semiconductor wafer with light to heat the substrate, thereby growing a silicide.
2. Description of the Background Art
Silicide technology that forms compounds (silicides) of silicon with metals for the purpose of increasing the performance of field-effect transistors (FETs) has been known. The formation of silicides reduces resistances in gates and source/drain regions to achieve the high-speed operation of the field-effect transistors. Examples of the metals that form silicides which are under study include nickel (Ni), cobalt (Co), and titanium (Ti). In particular, nickel is promising as the most suitable material for finer geometries. Japanese Patent Application Laid-Open No. 2011-14567 discloses a technique in which a nickel film is deposited on a silicon layer and heat treatment is performed using an electric furnace or a lamp annealer to form nickel silicide.
Conventionally, the heat treatment for the formation of nickel silicide requires treatment time in the range of tens of seconds to 100 minutes or more. In the silicide technology, for example, disclosed in Japanese Patent Application Laid-Open No. 2011-14567, the heat treatment time is not less than 15 minutes and is less than 120 minutes when the electric furnace is used, and the heat treatment time is not less than 15 seconds and is not more than 5 minutes when the lamp annealer is used.
However, when the heat treatment is performed for such a long time, the nickel silicide abnormally grows laterally (in a direction from the source/drain regions to the gate) to break through source/drain junctions, thereby giving rise to a problem in that leakage current increases rapidly.